PROGRESS IN BIOLOGICAL INQUIRIES, 1956 AT 
fish died in the river just below West Point. Tests made of the 
oxygen-consuming capacity of the waters showed a high value for 
areas below the pump mill at West Point. The effluent of this mill 
has many compounds which become oxidized readily in the river 
and thus tend to lower the dissolved oxygen of the water for a distance 
below the mill. 
Yo determine whether or not there existed a normal plankton cycle 
in the York River biweekly samples were taken throughout the year 
and the quantity of available oyster food measured. A maximum 
plankton crop in the. York River was observed at the usual vernal 
period, March to April. Shght increases were again noted in Novem- 
ber and December. These fall increases did not exceed the spring’ 
maxima. Throughout the summer the amount of plankton remained 
comparatively low. There was a larger nanno-plankton crop in the 
upper York River than in the lower throughout the major part of 
the year. The average plankton in the York River appears to be nor- 
mal and sufficient, and to constitute a greater amount of available food 
than is present in the Piankatank River where the oysters are, in 
general, fatter. 
Since the chief source of pollution in the York River results from 
the effluent of a paper mill at West Point, studies were carried on 
testing the action of this polluting material on oysters and on oyster 
food. 
Using the diatom Witeschia closterium as a test organism for labo- 
ratory experiments in determining the effects of polluting materials 
from the pulp mull, tests were carried on at the Washington labora- 
tory. The organisms were artificially cultured in a media of Miquel’s 
solution and sea water. Pulp-mill effluent was diluted to various con- 
centrations with the culture solution to determine the effect it had on 
the growth of this diatom. It was found that concentrations from 
1:1,000 to 1: 100,000 definitely stimulated growth. Concentrations 
greater than 1:500 inhibited -growth. Concentrations less than 
1: 100,000 showed little or no stimulation when compared with con- 
trol cultures. 
In view of the fact that it is impossible for the oyster to feed dur- 
ing the time the shell is held closed, experiments were carried on 
testing the effect of pulp-mill effluent on the number of hours per 
day oysters were open. A total of 74 oysters were examined during 
the course of the experiment. Of this total, 50 oysters were exposed 
to concentrations of pulp-mill effluent in sea water ranging from 100 
parts per thousand to 1 part in 10,000. Definite reductions in the 
number of hours the oysters were open occurred in concentrations 
down to 1 part of effluent in 5,000 parts of sea water. The results 
with weaker concentrations were less definite. This reduction oc- 
curred immediately after exposure in the stronger concentrations and 
after an exposure of 3 or 4 days in the weaker concentrations. A re- 
duction in the number of hours open per day in a strength of 1 part 
in 10,000 occurred after an exposure of 23 days. 
Using the carmine cone method developed. by Dr. Galtsoff, experi- 
ments were carried on to determine the minimum dose of effluent that 
would cause a depression in the ciliary activity of oysters. Other 
studies were made using this method to test the recovery after treat- 
ment, tolerance, and sensitivity. The general results of 22 experi- 
